e2e: Add clear_mem

We can't rely on having memset_s, so add our own equivalent that
declares itself volatile.

Signed-off-by: Dr. David Alan Gilbert <dave@treblig.org>

1 files changed, 15 insertions, 0 deletions

diff --git a/matrix-e2e.c b/matrix-e2e.c
index 71c1426..b2c3dd4 100644
--- a/matrix-e2e.c
+++ b/matrix-e2e.c
@@ -31,6 +31,21 @@ struct _MatrixE2EData {
     gchar *device_id;
 };
 
+/* Really clear an area of memory */
+static void clear_mem(volatile char *data, size_t len)
+{
+#ifdef __STDC_LIB_EXT1__
+    /* Untested! */
+    memset_s(data, len, '\0', len);
+#else
+    size_t index;
+    for(index = 0;index < len; index ++)
+    {
+        data[index] = '\0';
+    }
+#endif
+}
+
 /* Sign the JsonObject with olm_account_sign and add it to the object
  * as a 'signatures' member of the top level object.
  * 0 on success